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Potential for denitrification in cereal soils of northern Australia after legume or grass-legume pastures

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Pu, G.-X., Saffigna, P. G. and Strong, W.M. (1999) Potential for denitrification in cereal soils of northern Australia after legume or grass-legume pastures. Soil Biology and Biochemistry, 31 (5). pp. 667-675. ISSN 0038-0717

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Article Link: https://doi.org/10.1016/S0038-0717(98)00154-0


A temperature-controlled (30°C) pot study was conducted to determine the effect of the addition of legume pasture residues on denitrification in soils from 3 sites which had supported 4-20 years of legume pastures. Denitrification after 12 days of incubation was measured from the percentage loss of 15N-nitrate (application rate: 40 kg N/ha) which was quantified by mass balance and daily gaseous emissions of N2 and N2O. Without added residues, soil after 20 years of Mitchell grass (Astrebla spp.)-naturalized medic (Medicago polymorpha) showed the highest potential for denitrification (53%, 1.8 kg N/ha per day) and soil after 4 years of lucerne pasture had the lowest (36%, 1.2 kg N/ha per day). Soil after 4 years of snail medic (M. polymorpha cv. Sava) lost 46% of applied 15N (1.5 kg N/ha per day). Denitrification losses of the 3 soils were significantly correlated with the amounts of soil water-soluble C. No emissions were detected from soil without added residues during the 2-3 days after waterlogging. Nitrogen losses measured by gas emissions were within the range from 78-136% of that measured by mass balance. The quantity and time pattern of N2O emission showed no significance to the total gaseous emission and constituted only a small part of total N gases emitted (0.8-4.1%). After a period of legume pasture, soil was likely to lose a substantial amount of N by denitrification, and the addition of plant material could promote denitrification if soil was subjected to heavy rainfall during the summer.

Item Type:Article
Subjects:Agriculture > Agriculture (General) > Soils. Soil science > Soil and crops. Soil-plant relationships. Soil productivity
Plant culture > Field crops > Forage crops. Feed crops
Live Archive:14 Mar 2024 00:11
Last Modified:14 Mar 2024 00:11

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